I think there was an issue during transfering the files or during install process.
1.) Install the Astroid plugin and the Template again

Hallo, thank you for the hint. My provider only gives me the possibility to set a firewall to the hole website (on, protocol, off). So if i set the firewall to off there is no difference in safing the settings. So this does not have an effect. I have the folder "administrator" protected with a password to prevent from unauthorized access. Can this be a problem? I think there is a problem safing the settings, i mean, somthing go wrong. I mean, the right from the provider/host is given to save the changes or so ...?

Hallo! I did it, i reinstalled the versions: astroid 2.6.4 and the framework 1.3.12. Joomla did it without an error, but there is no difference in behaviour. Settings can be safed but on reload the template options the old settings are loaded, no changes are made ... any other ideas? I hope to get it work, it´s an important project ... thank you!

Hallo everybody,
i reinstalled with an tool of my provider all the joomla-files, reimported an actual version of the mysql database an tried it again. So joomla is running fine, but everytime i enter the template jp_perfect and make a change in the options it ist the same problem again. What i found out is, that the settings are safed BUT the changes are not shown in the backend. Example: I set the offcanvas size from befor 340px to new 344px, safed the settings, leafed the template and reload it. So in the backend the option is set to 340px (see picture). But if i call the site in frontend and check the size, the changes are made to 344px. So it seems so that changes are safed but NOT SHOWN in backend? It is the same for example with other options like layout-settings or what else. I need to fix the problem to run the website with the jp_perfect template.

How can i solve the problem? Please help! Thank you ...

Hello, if you developing a website please disable all Joomla / PHP Cache systems, joomla cache and use a Browser without any Add On like AdBlocker and so on.

Ok, i tried following things:

PHP Version 8.0.28, nginx-caching set off, joomla server caching set off, joomla system plugin cache deactivated, opcache.enable on the server can not be set to of (not allowed by the provider).

memory_limit 256M
max_execution_time 600
max_input_time 60 (Standard)
post_max_size 96M
upload_max_filesize 96M
opcache.enable on (Standard)

I tried two actual browsers (firefix and edge) with supported versions of astroid, no addons installed, browser chache cleared.

So the error is still present on the server of the provider. But one new thing is i noticed, when i change settings in the template options, safe them and reload the template options the value are set to the old on (as it was). But if i press F5 to reload the template option site, the value is actualized! I also notized, the very often the green button for changes made is blinking, so i have to press the save button a lot of times, although no changes are made by user.

If i use my installation local on XAMPP an set php to version 8.0.19, set opcache.enable on and set also all other joomla cache options "on", use the same memory_limit and so on as on the online server, the template options in the backend work fine. So i can not reproduce the error.